The present invention relates to a load adjustment device having a regulating element which can act on a setting member which determines the power of an internal combustion engine, and cooperates with a driver coupled with an accelerator pedal, and can be controlled, in addition, by an electric setting drive which cooperates with an electronic control unit.
On load adjustment devices, particularly load adjustment devices cooperating with carburetors or injection pumps, optimum control of an internal combustion engine over the entire load range is necessary. For this, a complicated construction or a complicated regulation of the corresponding load adjustment device has been necessary. Thus carburetors, for instance, in addition to the actual means for forming the mixture, have additional devices such as leaning, starting, idling, accelerating and economizing devices, etc. These devices complicate the construction of the carburetor and result in increased expense for structural parts, in particular, for instance, additional injection nozzles, pumps, special developments of the nozzle needles and separate air feeds, entirely aside from the high requirement as to regulation connected therewith.
In load adjustment devices there is of particular importance a control of the state of load upon idling, where only minimum power is given off by the internal combustion engines. This however, under certain circumstances and specifically in motor vehicles, is in contradistinction to load consuming devices which require a large amount of power, such as blowers, rear window heater, air conditioners, etc. In order to take these possible power requirements into account, control of the load adjustment device between a maximum idle position and a minimum idle position is necessary. Upon failure of the control, an emergency idle position of the setting member or regulating element is to be assured.
In contradistinction to the problems described above, load adjustment devices of the type are used, as a general rule, in cases in which the accelerator pedal and the setting member are electronically connected with each other. The accelerator pedal is coupled to the driver and the latter is coupled to a regulating element. Furthermore, a desired-value detection element associated with the driver is provided, as well as an actual-value detection element which cooperates with it and acts on an electric setting driver. The electric setting driver is adapted to be controlled by an electronic control device as a function of the values detected.
The electric connection of accelerator pedal and setting member to the interposed electronic control device makes it possible to set desired-value positions predetermined by the accelerator pedal and the driver coupled to it, with reference to the actual-values established by the position of the regulating element and the setting member. The connection makes it possible to check the pedal and the driver for the existence or absence of plausibility conditions. Thereby, when given plausibility conditions are present or absent there is the possibility, via the electronic control device, to act on the setting member, which can be developed, for instance, as throttle valve or injection pump, in corrective fashion by controlling the electric setting drive. Thus, for instance, intervention by the electronic control device can be provided in order to avoid wheel slippage upon starting, due to a giving of too much power by the gas pedal. Other automatic interventions into the load adjustment device are, for instance, conceivable in the case of automatic shifting of a transmission or a speed governor control or in the case of the previously discussed idle control of the internal combustion engine.